Effect of zinc and multivitamin supplementation on the growth of Tanzanian children aged 6-84 wk: a randomized, placebo-controlled, double-blind trial

Background: Poor child growth increases risks of mortality and morbidity. Micronutrient supplements have the potential to improve child growth. Objective: We assessed the effect of daily zinc, multivitamin (vitamins C, E, and B-complex), and zinc and multivitamin (Zn+MV) supplementation on growth in infants in Tanzania. Design: In this randomized, 2 X 2 factorial, double-blind trial, 2400 infants were randomly assigned to receive zinc, multivitamins, Zn+MVs, or a placebo at 6 wk of age and were followed up for 18 mo with monthly growth measurements. Mixed-effects models with restricted cubic splines for the mean change in anthropometric z scores were fit for each group. Likelihood ratio tests were used to compare the effect of supplements on growth trajectories. Cox proportional hazards models were used to compare incidences of stunting, wasting, and underweight. Results: Children in all groups experienced growth faltering. At 19 mo of age, prevalences of stunting, wasting, and underweight were 19.8%, 6.0%, and 10.8%, respectively. Changes in weight-for-age z scores (WAZs) and weight-for-height z scores (WHZs) were significantly different across the 4 groups (P < 0.001 for both). The mean SE decline in the WAZ from baseline to the end of follow-up in the Zn+MV group was significantly less than in the placebo group (-0.36 +/- 0.04 compared with 0.50 +/- 0.04; P = 0.020), whereas the decline in the WHZ was significantly greater in the zinc-only group than in the placebo group (-0.57 +/- 0.07 compared with 0.35 +/- 0.07; P = 0.021). Supplements did not have a significant effect on mean change in the height-for-age z score or on rates of stunting, wasting, or underweight. Conclusions: Although there were small but significant improvements in the WAZ in the Zn+MV group, daily zinc supplementation alone, multivitamin supplementation alone, and the combined Zn+MV did not reduce the incidences of underweight, stunting, or wasting in Tanzanian infants. Alternative approaches to prevent growth faltering should be pursued. This trial was registered at clinicaltrials.gov as NCT00421668.